Cephalexin-d 5 (monohydrate) is the deuterium labeled Cephalexin monohydrate. Cephalexin monohydrate is a potent, orally active and the first-generation cephalosporin antibiotic. Cephalexin monohydrate kills gram-positive and some gram-negative bacteria by disrupting the growth of the bacterial cell wall. Cephalexin monohydrate is used for the research of pneumonia, strep throat, and bacterial endocarditis, et al.